Reply to "MTH Amtrak Superliner LED Upgrade in Pictures"

stan2004OGR Forum Member

Ron_S posted:
...trying it without a resistor would light the red led but nothing on the led strip.

Right. Without a resistor, the marker LEDs would siphon ALL the current from GRJ's board and hence extinguish the LED strip. Adding external resistance limits how much the marker LEDs steal from the strip. Going the other way, if you add too much external resistance - say, 10K or more, the marker LEDs steal very little...but be unusably dim.

4/27/191:32 PM

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